Originally Posted by
TheOtherDave™
Exactly.
If you're in the snowbelt and/or routinely operate the car in sub-freezing temps, 10w30 offers better protection when the motor is stone cold.
Otherwise, use 5w30 and let the motor come up to temp before wailing on it.
Really, should I put 10w30 during winter? I'm gonna have to start it early every morning this winter.